P027F
Cold Start Fuel Injection Quantity A Higher Than Expected.
- Generic
- Powertrain
- Generic code
- Medium severity
How this code is built
- P
- SystemPowertrain
- 0
- Defined bySAE, the same on every car
- 2
- AreaFuel and air metering (injector circuit)
- 7F
- FaultThe specific fault in that area
What it means
P027F means the engine control unit calculated or commanded more fuel during a cold start than it expected for the conditions. It is set when the cold start injection quantity (bank or group A, depending on the vehicle) is above the allowed limit. Exact monitoring and thresholds vary by manufacturer and engine type, so check the model-specific procedure.
Symptoms
- Engine management light on
- Rough or unstable idle after a cold start
- Smell of fuel or black smoke from the exhaust on cold start
- Hard starting or long cranking when cold
- Poor fuel economy
- Fuel-contaminated engine oil (rising oil level or fuel smell on the dipstick)
Possible causes
- Coolant temperature sensor or its wiring giving a falsely low reading, causing excessive cold start enrichmentlikely
- Leaking or sticking injector delivering too much fuellikely
- Fuel pressure too high or uncontrolled (regulator, pump control or rail pressure sensor fault, depending on the fuel system)possible
- Air leak or faulty air mass or manifold pressure sensor making the system add extra fuel to compensatepossible
- Intake air temperature sensor fault or wiring problem skewing the cold start fuel calculationpossible
- Poor connections or damaged wiring to the injectors or related sensorspossible
- Outdated or faulty engine control unit calibration, where the manufacturer has issued an update for this faultrare
How to diagnose
- Read all stored and pending codes and the freeze frame data, noting coolant temperature, intake air temperature, engine load and rail or fuel pressure at the time the code set.
- Look for related codes (sensor, fuel trim, rail pressure, injector) and deal with those first.
- With a fully cold engine, compare the live coolant and intake air temperatures with each other and with ambient temperature.
- Inspect the wiring and connectors of the temperature sensors, injectors and pressure sensors for damage, corrosion or water ingress.
- Check for intake air leaks, split hoses and unmetered air, then review the air mass or manifold pressure readings and fuel trims against expected values.
- Check live fuel pressure against the specification for your engine, both at cold start and at idle.
- Check the engine oil for fuel dilution, and look for signs of injector leakage such as fuel smell or wet spark plugs.
- Perform an injector leak-down or balance test using the procedure for the specific engine, then check for any manufacturer software update or technical bulletin.
How to fix
- Replace the coolant or intake air temperature sensor, or repair its wiring, if it reads incorrectly.
- Replace any leaking or sticking injector, and change the engine oil and filter if fuel dilution is found.
- Repair or replace the faulty fuel pressure control component or pressure sensor, following the model-specific procedure.
- Repair air leaks or replace a faulty air mass or manifold pressure sensor.
- Repair damaged wiring or connectors, then clear the code and road test to confirm it does not return.
- Apply an engine control unit software update if the manufacturer lists it as a fix for this fault.
Can I keep driving?
Medium severity
The car can usually be driven for a short time, but get it checked soon. Excess fuel on cold starts can dilute the engine oil, foul plugs and harm the catalytic converter, so avoid long journeys until it is diagnosed.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.